Data communication control apparatus and its control method, image processing apparatus and its method, and data communication system

ABSTRACT

In video conference system terminals, the conventional difficulty in high-quality display of facial expressions of a plurality of participants is solved. In a multipoint connection device connecting a plurality of video conference terminals, image data transmitted from a terminal is decoded, and a face area in the image data is recognized. Then, quantization coefficients for the face area are set to be greater coefficients than those for other areas than the face area, then the image data is compressed, and delivered to the respective terminals. By this arrangement, in image data, a face area with great significance can be re-compressed without degradation of image quality, while an area with less significance such as background can be compressed with high efficiency. Thus, the total code amount can be reduced. Accordingly, even if the system uses a narrow band communication channel, the significant face area can be clearly displayed at the respective terminals.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a data communication controlapparatus and its control method, an image processing apparatus and itsmethod, and a data communication system which realize interactive videocommunication among a plurality of points.

[0002] A multipoint video conference system widely used now enablesvideo conference terminals based on the ITU-T Recommendation H. 320 andthe like to perform interactive communication among a number of pointsvia a multipoint connection device.

[0003] As standards related to the multipoint connection device tocontrol such multipoint connection among video conference terminals, theITU-T Recommendation H. 231 defining the functional construction of themultipoint connection device and the format of multipoint communication,the ITU-T Recommendation H. 243 determining an in-channel communicationprocedure and the like have been made.

[0004]FIG. 1 shows the construction of a conventional video conferencesystem. In FIG. 1, a multipoint connection device 22 interconnects videoconference terminals 21 a to 21 n at three or more points, and performsaudio mixing, video data delivery control or video data combining forsplit screen view, further, performs presidential control over theconference. In this manner, a multipoint conference connecting aplurality of remote points can be realized by connecting terminals via amultipoint connection device as long as the terminals are based on theRecommendation H. 320.

[0005] To realize multipoint interactive video communication in a videoconference system based on the Recommendation H. 320, to deliver imagedata from the multipoint connection device 22 to the video conferenceterminals 21 a to 21 n as shown in FIG. 1, the following methods (1),(2) and the like have been put into practical use:

[0006] (1) A method to deliver a video image from a specific videoconference terminal designated by a presidential terminal to therespective video conference terminals.

[0007] (2) As shown in FIG. 10, a method to reduce video images fromrespective video conference terminals 21 a to 21 n in the multipointconnection device 22, so as to simultaneously deliver images fromrespective video conference terminals 21 a to 21 n within a limitedband.

[0008] Note that in FIG. 10, numerals 31 a to 31 d denote video datatransmitted from the respective video conference terminals 21 a to 21 d;32, reduced and synthesized video data delivered from the multipointconnection device 22 to the respective video conference terminals 21 ato 21 d.

[0009] Further, to realize a video conference system in an Internetenvironment, software programs such as CU-SeeMe by White Pine Software,Inc. have been provided. In the multipoint video conference system,image data transmitted from the respective client terminals aredelivered via a multipoint connection server to the respective clientterminals without any processing. FIG. 11 shows video data transfer inthis system. In FIG. 11, numerals 41 a to 41 c denote client terminalsrealized by personal computers or the like having video and audioinput/output functions; 42, a multipoint connection server whichdelivers video and audio data from the respective client terminals 41 ato 41 c to the client terminals 41 a to 41 c without any processing.

[0010] However, the conventional video conference system using themultipoint connection based on the Recommendation H. 320 or the like, inwhich communication is performed within a limited band to the respectiveterminals, has problems as follows.

[0011] (1) Only the video image of a particular reference participant isdelivered; or

[0012] (2) As reduced images of plurality of participants aretransmitted, the images of the respective speakers are unclear.

[0013] In the video conference terminal, it is difficult tosimultaneously and clearly display a plurality of conferenceparticipants.

[0014] Further, in the video conference system utilizing the Internet asshown in FIG. 11, the multipoint connection server 42 delivers video andaudio data from the respective client terminals 41 a to 41 c to theclient terminals 41 a to 41 c without any processing. For example,between the multipoint connection server 42 and the client terminal 41a, the client terminal 41 a transmits terminal information A to themultipoint connection server 42, and the multipoint connection server 42transfers terminal information B and C from other client terminals 41 band 41 c to the client terminal 41 a. Accordingly, the code amount ofthe image data delivered from the multipoint connection server 42 to theclient terminals 41 a to 41 c increases in proportion to the number ofconference participants (terminals). If a sufficient band is not ensuredas a communication channel, the frame rate of images received by theclient terminals 41 a to 41 c is extremely reduced. Accordingly, todisplay a received image, so-called frame thinning, i.e., omitting aframe at predetermined intervals, must be performed.

SUMMARY OF THE INVENTION

[0015] Accordingly, it is an object of the present invention to providea data communication control apparatus and its control method and a datacommunication system which enable high-quality image communication. Itis another object of the present invention to provide a datacommunication control apparatus and its control method and a datacommunication system which enables image communication without degrationof the quality of the important portion of an image even if using anarrow band communication channel.

[0016] According to the present invention, the foregoing objects areattained by providing a data communication control apparatus comprising:compression means for compressing image data to be transmitted;communication means for transmitting the image data compressed by thecompression means to the terminals; recognition means for recognizing aspecific area in the image data; and compression control means forcontrolling a compression method in the compression means in accordancewith whether or not an object area in the image data is the specificarea.

[0017] It is another object of the present invention to provide a datacommunication control apparatus and its control method and a datacommunication system which enable clearly displayed facial expressionsof participants in a multipoint video conference system.

[0018] According to the present invention, the foregoing object isattained by providing the data communication control apparatus whereinthe specific area is an area showing a person's face.

[0019] It is further object of the present invention to provide an imageprocessing apparatus and its method which mitigate degradation of imagequality upon reuse of compressed image data.

[0020] According to the present invention, the foregoing object isattained by providing an image processing apparatus comprising:recognition means for recognizing a-specific area in an imagerepresented by compressed image data; and compression control means forcontrolling a re-compression method for re-compressing the compressedimage data based on recognition by the recognition means.

[0021] Other features and advantages of the present invention will beapparent from the following description taken in conjunction with theaccompanying drawings, in which like reference characters designate thesame name or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in andconstitute a part of the specification, illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

[0023]FIG. 1 is a block diagram showing the construction of a multipointvideo conference system according to a first embodiment of the presentinvention;

[0024]FIG. 2 is a block diagram showing the basic construction of amultipoint connection device;

[0025]FIG. 3 is an example of display screen of a video conferenceterminal;

[0026]FIG. 4 is a flowchart showing image processing by the multipointconnection device;

[0027]FIG. 5 is an example of image delivered in the first embodiment;

[0028]FIG. 6 is a block diagram showing the basic construction of themultipoint connection device according to a second embodiment of thepresent invention;

[0029]FIG. 7 is a flowchart showing image processing by the multipointconnection device;

[0030]FIG. 8 is an example of a spatial filter;

[0031]FIG. 9 is a block diagram showing the construction of themultipoint connection device according to a third embodiment of thepresent invention;

[0032]FIG. 10 is an example of image processing by the conventionalmultipoint connection device; and

[0033]FIG. 11 is a block diagram showing an Internet-type multipointvideo conference system.

[0034]FIG. 12 is a block diagram showing the another construction of amultipoint connection device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Preferred embodiments of the present invention will now bedescribed in detail in accordance with the accompanying drawings.

First Embodiment

[0036] The basic construction of a video conference system according toa first embodiment of the present invention is similar to that of theabove-described prior art as shown in FIG. 1. The video conferenceterminals 21 a to 21 n (hereinbelow, simply referred to as “terminals”)at three or more points are interconnected via the multipoint connectiondevice 22. Image data outputted from the respective terminals 21 a to 21d are delivered to the other terminals via the multipoint connectiondevice 22.

[0037]FIG. 2 is a block diagram showing the basic construction of themultipoint connection device 22 in the present embodiment. In FIG. 2,numerals 11 a to 11 n denote network interface units for accommodatingthe remote terminals 21 a to 21 n, as line interfaces for ISDN, PSTN andthe like; and 12 a to 12 n, multiplexing/demultiplexing units whichperform multiplexing/demultiplexing on various image, audio and controldata in accordance with, e.g., the ITU-T Recommendation H.221. Note thatin the multipoint connection device 22, the number of the networkinterface units 11 a to 11 n and that of the multiplexing/demultiplexingunits 12 a to 12 n correspond to the number of video conferenceterminals which can be directly connected to the multipoint connectiondevice. Further, the multipoint connection device 22 can be connected toanother multipoint connection device, a server or the like via thenetwork interface units 11 a to 11 n and the multiplexing/demultiplexingunits 12 a to 12 n.

[0038] Numeral 13 denotes an audio processor which performsdecompression/mixing processing on audio code data, transmitted from therespective terminals 21 a to 21 n and demultiplexed by themultiplexing/demultiplexing units 12 a to 12 n, then performscompression encoding on the data again, and delivers the data to therespective terminals 21 a to 21 d. Numeral 14 denotes an image decoderwhich decodes compressed image code data demultiplexed by themultiplexing/demultiplexing units 12 a to 12 n, thus generatinguncompressed image data.

[0039] Numeral 15 denotes a face-area recognition unit which recognizesa face area of a person from image data decoded by the image decoder 14;16, an image encoder which again compresses the image data decoded bythe image decoder 14; and 17, a quantization controller which performsquantization control upon re-compression by the image encoder 16, inaccordance with the result of face area recognition by the face-arearecognition unit 15. More specifically, a plurality of quantizationtables are prepared, and if it is determined that a quantization objectimage is not a face area image, a quantization table is selected suchthat coefficients of the table are set for a quantization step greaterthan that used in decoding.

[0040] Numeral 18 denotes a system controller which performs variouscommunication protocol processing and the entire operation of themultipoint connection device 22.

[0041]FIG. 3 is an example of image displayed on the terminals 21 a to21 n in the multipoint video conference system of the presentembodiment. Assuming that the image in FIG. 5 is a displayed image onthe terminal 21 d, numeral 71 denotes a window to display a video imageof a user of the terminal 21 d; 72 a to 72 c, windows to display videoimages of users of the other terminals (e.g., 21 a to 21 c) asparticipants of the conference; and 73, a common window in theconference to display, e.g., a white board.

[0042] Next, image processing by the multipoint connection device 22will be described in detail with reference to the flowchart of FIG. 4.

[0043] Multiplexed multimedia data sent via the communication interfaceunits 11 a to 11 n accommodating the terminals 21 a to 21 n areframe-demultiplexed by the multiplexing/demultiplexing units 12 a to 12n, and audio compressed data, video compressed data, data conferencelow-speed data, system control data and the like are extracted (stepS1001). Hereinbelow, processing on the demultiplexed video compresseddata will be described.

[0044] Note that the demultiplexed audio compressed data is decompressedby the audio processor 13, and mixed with other decompressed audio datademultiplexed by the respective multiplexing/demultiplexing units 12 ato 12 n. Then, the mixed audio data is compressed, multiplexed withother data such as image data by the multiplexing/demultiplexing units12 a to 12 n, and delivered to the respective terminals 21 a to 21 n.

[0045] The system controller 18 determines whether or not code amountcontrol is performed on the demultiplexed video compressed data inaccordance with an instruction from a terminal as a delivery destinationof the data (step S1002). If the code amount control is not performed,the video compressed data is multiplexed again with other data by themultiplexing/demultiplexing units 12 a to 12 n (step S1009). In thisarrangement, regarding a video image from a specific terminal, specifiedby a user, if the user instructs not to perform the above-described codeamount control, the video image can be delivered as a fine image with aclear background image.

[0046] On the other hand, if the code amount control is performed, thevideo compressed data is decoded by the image decoder 14 (step S1003),and temporarily stored in a RAM (not shown) or the like in the imagedecoder 14. Then the face-area recognition unit 15 performs face arearecognition processing on the decoded image data (step S1004). Note thatas the face area recognition by the face-area recognition unit 15, anarea including a person's face can be recognized by, e.g., a methoddescribed in “Extraction of Plural Face Areas from a Natural Image byUsing Genetic Algorithm” (Yokoo and Hagiwara, The Institute ofElectrical Engineers of Japan Proceedings C, Vol. 117-C, No. 9,September, 1997) or the like.

[0047] Note that in the present embodiment, the face area recognitionmethod is not limited to any particular method, but any method can beused. A higher level recognition method such as extraction of exact facearea outline can be employed as long as the multipoint connection devicehas sufficiently high processing capability. Further, in some face arearecognition method, it is not necessary for the image decoder 14 tocompletely decode the image data.

[0048] After the face area recognition, the decoded image data isre-compressed by the image encoder 16. In the present embodiment, uponcompression processing, the quantization coefficients are controlledbased on the result of face area recognition.

[0049] The result of face area recognition is outputted to thequantization controller 17. The quantization controller 17 hasquantization coefficients used in decoding by the image decoder 14 (or Qfactors for quantization) and quantization coefficients multiplied by n(n>1). Note that-the former quantization coefficients-are set as defaultcoefficients.

[0050] Regarding an area determined at step S1005 as a non-face area,the quantization coefficients having the set default values are changedto the quantization coefficients multiplied by n (step S1006). Note thatregarding an area determined as a face area, the same quantizationcoefficients (default values) as those in the decoding are used.

[0051] Then, the image encoder 16 performs quantization based on the setquantization coefficients on the image data held in the image decoder14, thus performing compression processing (step S1007).

[0052] In this arrangement, a face area with great significance isre-compressed without degrading image quality, while an area other thanthe face area such as background with less significance is compressed bya greater quantization step. Thus the total code amount can be reduced.

[0053] The multipoint connection device 22 performs the aboveprocessings independently on data transferred from the respectiveterminals 21 a to 21 n. Note that the re-compressed image data aremultiplexed with the audio compressed data by themultiplexing/demultiplexing units 12 a to 12 n (step S1008), anddelivered to the respective terminals 21 a to 21 n in accordance with acommunication protocol.

[0054]FIG. 5 is an example of displayed image, obtained by e.g. a camera(not shown) of the terminal 21 d, then processed by the multipointconnection device 22 as described above, and delivered to the respectiveterminals 21 a to 21 n, in the video conference system of the presentembodiment. In FIG. 5, an area in a circle 51 is recognized as a facearea; and an area 52 is a background area recognized as a non-face area.The background area 52, quantized by a greater quantization step,becomes a low-resolution image, while the face area 51 has image qualityequivalent to that of an image obtained by the terminal 21 d.

[0055] As described above, according to the present embodiment, in avideo conference system, only a significant portion of an image obtainedby a terminal can be transmitted with high precision to the respectiveterminals of video conference system. Accordingly, even if therespective terminals are connected by a narrow band communicationchannel, the significant portion can be transmitted in high-qualityimage communication. At the respective terminals, in an imagetransferred from another terminal, a significant portion, face area,i.e., the facial expression of the user of the other terminal can beclearly displayed without reduction or frame thinning.

[0056] Further, in response to an instruction from a terminal, an imagefrom another arbitrary terminal may be received as an entirely highquality image at any time.

[0057] Note that the decoding processing and the encoding processing inthe present embodiment may be performed in predetermined image datablock units. In this case, the above-described processings at stepsS1003 to S1007 are repeated in each block.

[0058] Further, an area where high image quality is maintained is notlimited to a face area. The same advantage as that of the presentembodiment can be obtained by setting an arbitrary significant object asan object of high-precision display in accordance with the content ofconference, and transferring other image areas with degraded imagequality.

Second Embodiment

[0059] Next, a second embodiment of the present invention will bedescribed.

[0060] As the basic construction of the video conference system of thesecond embodiment is similar to that of the first embodiment as shown inFIG. 1, the explanation of the construction will be omitted.

[0061]FIG. 6 is a block diagram showing the construction of themultipoint connection device 22 according to the second embodiment ofthe present invention. In FIG. 6, constituents corresponding to those inFIG. 2 have the same reference numerals and the explanations of theseconstituents will be omitted.

[0062] In FIG. 6, numeral 86 denotes a spatial filter processor whichperforms low-frequency filter processing on decoded image data based onthe result of recognition by the face-area recognition unit 15. Morespecifically, the spatial filter processor 86 performs spatial filterprocessing on areas other than a face area by a low-pass filter, toattenuate high frequency components.

[0063] Next, the image processing by the multipoint connection device 22according to the second embodiment will be described in detail withreference to the flowchart of FIG. 7. Note that steps corresponding tothose in FIG. 4 have the same step numbers, and the explanations ofthose steps will be omitted.

[0064] As in the case of the first embodiment, after the face arearecognition at step S1004, the decoded image data is re-compressed bythe image encoder 16. In the present embodiment, upon this compressionprocessing, spatial filter processing is performed based on the resultof face area recognition.

[0065] The spatial filter processor 86 inputs decoded image data and theresult of face area recognition. In the spatial filter processor 86, alow-pass filter is prepared in advance, and spatial filter processing bythe low-pass filter is performed (step S1106) on an area determined atstep S1005 as a non-face area. Then, the spatial filter processed imagedata is compressed by the image encoder 16 (step S1008).

[0066]FIG. 8 is an example of the low-pass filter in the spatial filterprocessor 86. The filter processing expressed by the following equation(1) is performed by using the low-pass filter.

P′(x,y)=(P(x−1,y−1)+P(x,y−1)+P(x+1,y−1)+P(x−1,y)+P(x,y)+(x+1,y)+P(x−1,y+1)+P(x,y+1)+P(x+1,y+1))/9   (1)

[0067] Note that P(x,y) is a pixel value of coordinates (x,y).

[0068] Note that the spatial filter in the second embodiment is notlimited to that as shown in FIG. 8, but any filter may be employed aslong as it is a low-pass filter.

[0069] Further, in the second embodiment, execution/non-execution ofspatial filter processing is controlled in accordance with whether ornot an object area is a face area (specific area), however, the presentinvention is not limited to this arrangement. For example, spatialfilter processing may be performed on a specific area and other areas.In this case, a low-pass filer used in the processing is selected inaccordance with whether an object area is a specific area or not. Afilter for the other areas than the face area is selected so as toremove high frequency components more than those in the face arearemoved by a filter for the face area.

[0070] As described above, according to the second embodiment, in imagedata, a specific area with great significance such as a face area isre-compressed without degrading image quality, and in areas other thanthe specific area with less significance such as background, highfrequency components are attenuated. This reduces the total code amount,and accordingly, obtains the same advantage as that of the firstembodiment.

[0071] Further, in the second embodiment, as the resolution of image iscontrolled by the spatial filter processing, degradation of imagequality is visually more inconspicuous in comparison with the firstembodiment where the code amount is reduced by control on quantizationcoefficients.

[0072] In the above-described first and second embodiments, in each ofthe images obtained by the respective video conference terminals,especially a face area is detected. In a case where the terminalsrespectively have a fixed camera which obtains an image with a fixedimage sensing area, if the compression rate for a part around the centerof the obtained image is set to a lower rate than the compression ratefor other parts in advance, the object of the present invention can beattained without detecting a face area from the image.

[0073] However, in a case where a plurality of persons are image-sensedby such fixed camera, in an image from a terminal, the user of theterminal is not always positioned around the center of the image.Accordingly, in this case, if the image transfer is performed such thatonly a part around the center of the obtained image has high imagequality, the transferred image is unnatural. For example, if only thehalf of the face of the user is included in a preset low compressionrate area but the other half is included in a high compression ratearea, it is impossible to transfer the image such that the entire facearea has high image quality.

[0074] Accordingly, even if the terminals respectively have a fixedcamera, to ensure high-quality face area transfer, a face area isextracted as a significant portion from an obtained image, as in thecase of the above-described first and second embodiments.

[0075] Further, in a case where the terminals respectively have a camerain which its image sensing direction can be operated from anotherterminal, the camera of a terminal may be operated such that the user'sface comes to the center of the obtained image. However, if theorientation of the camera can be arbitrarily operated from theopposite-end terminal side, an undesirable portion such as backgroundother than a person's face might be arbitrarily image-sensed.

[0076] Accordingly, in case of image sensing by such remote-controllablecamera, detecting a face area is rather advantageous than previouslysetting low compression rate area and high compression rate area withinthe obtained image. The face area detection unnecessitates operation ofthe orientation of the camera, and further ensures privacy protectionfor conference participants.

Third Embodiment

[0077] Next, a third embodiment of the present invention will bedescribed. The basic construction of the video conference system of thethird embodiment is similar to that of the first embodiment as shown inFIG. 1, therefore, the explanation of the construction will be omitted.

[0078] In the third embodiment, the principal processings of themultipoint connection device 22 having the functions as described in thefirst embodiment are realized by software.

[0079]FIG. 9 is a block diagram showing the construction of themultipoint connection device 22 according to the third embodiment of thepresent invention. Numeral 61 denotes a communication interface unit forcommunication with an ISDN, a PSTN and the like; and 62, a mediaprocessor which performs principal signal processings. The mediaprocessor 62 performs various digital signal processings by aspecialized processor for multimedia signal processing, a DSP (DigitalSignal Processor) and the like. In the third embodiment, the videoconference system can be realized with a simple and low-costconstruction without preparing dedicated hardware, by processing variousdata by multitask processing by utilizing the media processor 62.

[0080] Numeral 63 denotes a RAM (Random Access Memory) which is used asa work memory necessary for the operation of the media processor 62 andas a buffer memory for various image and audio data to be processed. TheRAM 63 is realized by, e.g., a high-speed large-capacity memory such asan SDRAM (Synchronous DRAM). Numeral 64 denotes a CPU which performssystem control for the multipoint connection device 22, communicationprotocol processing and the like; 65, a RAM used as a work buffernecessary for the operation of the CPU 64; and 66, a ROM (Read OnlyMemory) in which a control program necessary for the operation of theCPU 64 and a control program necessary for the operation of the mediaprocessor 62 are stored. The program necessary for the operation of themedia processor 62 is transferred from the ROM 66 to the RAM 63 uponsystem initialization.

[0081] In the third embodiment, the above construction realizesprocessing as shown in the flowchart of FIG. 4.

[0082] That is, a control program to realize the processing is stored inthe ROM 66 in advance. The program is developed on the RAM 63 or the RAM65, and executed by the media processor 62 or the CPU 64. For example,processing related to data compression/decompression is performed by themedia processor 62, and other processings are controlled by the CPU 64.

[0083] According to the third embodiment, the same advantages as thosein the first embodiment can be obtained by realizing the processingsdescribed in the first embodiment by software.

[0084] Note that in the third embodiment, the multipoint connectiondevice 22 as described in the first embodiment is realized by software.Similarly, the multipoint connection device 22 as described in thesecond embodiment may be realized by software.

[0085] Note that the compression method employed in the above-describedfirst to third embodiments may be any method. For example, an H. 261coding method or the like based on DCT (Discrete Cosine Transformation)used in the Recommendation H.320 may be used. In such case, the controlon the compression method (quantization coefficients) based on theresult of specific-area recognition is performed in macroblock units.

[0086] Further, the compression control method of the present inventionis not limited to the quantization control or spatial filter control asdescribed in the first to third embodiments, but any control method maybe performed as long as it controls the degree of image qualitydegradation due to re-compression in accordance with whether or not anobject area is a specific area. In other words, any control method maybe used as long as it controls the compression rate in re-compression.

[0087] In addition, more flexible image quality control includingfurther improvement in image quality of delivered image data can berealized by combining the quantization control described in the firstembodiment and the spatial filter control described in the secondembodiment.

[0088] Further, in the first and second embodiments, the videoconference terminals are directly connected to a public line such asPSTN/ISDN line, however, the present invention is not limited to thisexample. The video conference terminals may be connected to theInternet, an Intranet or the like. In this case, as shown in FIG. 12,communication is performed with a plurality of terminals by the InternetProtocol via a network access controller 121 having a LAN interface suchas the Ethernet. The means for communication with the respectiveterminals is logically constructed for each terminal. Control onpacketized data and data multiplexing/demultiplexing processing areperformed by the network access controller 121 and a system controller122.

[0089] Further, the video conference terminals connected to themultipoint connection device of the present invention may be dedicatedterminals or general-purpose terminals such as personal computers wherea predetermined application (software) program is operated.

[0090] Further, the multipoint connection device of the presentinvention may have an automatic HTML (Hyper Text Markup Language) datagenerating function and an HTTP (Hyper Text Transfer Protocol) serverfunction in addition to the function related to multipoint terminalconnection. In this case, general-purpose communication terminals, whichdisplay and visualize image and audio data stored in the HTTP server ofthe multipoint connection device, can be connected to the multipointconnection device. As the general-purpose communication terminals,personal computers having a so-called WWW-browser and network computerscan be employed. Further, by virtue of recent development ofsemiconductor technologies, these computers may be employed as quick andconvenient terminals even in a mobile communication environment. Thesegeneral-purpose communication terminals are IP (InternetProtocol)-connected to the multipoint connection terminal via a publicnetwork such as an ISDN or a PSTN or a LAN (Local Area Network). Thisenables interconnection among the existing video conference terminalsand the general-purpose terminals such as personal computers and networkcomputers.

Other Embodiment

[0091] The present invention can be applied to a system constituted by aplurality of devices (e.g., a host computer, an interface, a reader anda printer) or to an apparatus comprising a single device (e.g., a copymachine or a facsimile apparatus).

[0092] Further, the object of the present invention can be also achievedby providing a storage medium storing program code for performing theaforesaid processes to a system or an apparatus, reading the programcode with a computer (e.g., CPU, MPU) of the system or apparatus fromthe storage medium, then executing the program.

[0093] In this case, the program code read from the storage mediumrealize the functions according to the embodiments, and the storagemedium storing the program code constitutes the invention.

[0094] Further, the storage medium, such as a floppy disk, a hard disk,an optical disk, a magneto-optical disk, CD-ROM, CD-R, a magnetic tape,a non-volatile type memory card, and ROM can be used for providing theprogram code.

[0095] Furthermore, besides aforesaid functions according to the aboveembodiments are realized by executing the program code which are read bya computer, the present invention includes a case where an OS (operatingsystem) or the like working on the computer performs a part or entireprocesses in accordance with designations of the program code andrealizes functions according to the above embodiments.

[0096] Further, a product obtained by the image processing method of thepresent invention, e.g., printed matter, is included in the presentinvention.

[0097] Furthermore, the present invention also includes a case where,after the program code read from the storage medium are written in afunction expansion card which is inserted into the computer or in amemory provided in a function expansion unit which is connected to thecomputer, CPU or the like contained in the function expansion card orunit performs a part or entire process in accordance with designationsof the program code and realizes functions of the above embodiments. Ina case where the present invention is applied to the aforesaid storagemedium, the storage medium stores program code corresponding to theflowcharts shown in FIGS. 4 and 7 described in the embodiments.

[0098] As described above, according to the present invention, in thevideo conference system in a narrow band communication channel, facialexpressions of the participants of a conference can be clearlydisplayed.

[0099] Further, upon re-compression on decompressed image data,degradation of image quality can be reduced.

[0100] As many apparently widely different embodiments of the presentinvention can be made without departing from the spirit and scopethereof, it is to be understood that the invention is not limited to thespecific embodiments thereof except as defined in the appended claims.

1-48. (canceled)
 49. A data communication control method for controllingdata communication among a plurality of terminals connected to amultipoint connection device, the method comprising the steps of:transferring image data from one of the plurality of terminals;recognizing a specific area in the transferred image data at themultipoint connection device; controlling the compression method forcompressing the received image data at the multipoint connection deviceto compress the specific area and not reduce a burden of the pluralityof terminals; and transmitting the compressed image data from themultipoint connection device to at least one of the plurality ofterminals.
 50. The method according to claim 49, wherein the transferredimage data is determined whether the specific area is compressed or not,according to a designation of at least one of the plurality ofterminals.
 51. The method according to claim 49, wherein the specificarea is an area in which a person's face is displayed.
 52. A multipointconnection device for controlling data communication among a pluralityof terminals, comprising: an interface unit which receives image datafrom one of the plurality of terminals; a recognition unit whichrecognizes a specific area in the received data; and a controller whichcontrols the compression method for compressing the received image datato compress the specific area and not reduce a burden of the pluralityof terminals, wherein the interface unit transmits the compressed imagedata to at least one of the plurality of terminals.
 53. The deviceaccording to claim 52, wherein the received image data is determinedwhether the specific area is compressed or not, according to adesignation of at least one of the plurality of terminals.
 54. Thedevice according to claim 52, wherein the specific area is an area inwhich a person's face is displayed.
 55. A computer readable mediumcontaining control program code in the multipoint connection device forcontrolling data communication among the plurality of terminals, thecontrol program code being implemented by a method comprising the stepsof: receiving image data from one of the plurality of terminals;recognizing a specific area in the received image data; controlling thecompression method for compressing the received image data to compressthe specific area and not reduce a burden of the plurality of terminals;and transmitting the compressed image data from the multipointconnection device to at least one of the plurality of terminals.